Using a Tunell filament monitor with overhead filament rack

[Bret Wortman]

I just purchased a Tunell monitor for my Rep2, and realized as I was preparing to install and mount it that my filament route doesn't come up from behind the replicator, but from an overhead 5-spool rack. I'm trying to figure out the best way to mount the monitor and I'm struggling to come up with ideas, honestly, that will work without interfering with the bot itself. Any thoughts?

[Ryan Carlyle]

Mount directly to the top of the extruder?

[Joseph Chiu (Toybuilder)]

How far up is the overhead rack?  My initial thought is that you could mount an inverted L shaped arm to the back of the Rep2 and mount the monitor to that.  If you make the arm with 2020 style extrusions, you could try using the 2020 profile bracket (http://www.thingiverse.com/download:792113).  Otherwise, I can probably CAD something up for you.

The other posibility is to mount a small arm off of your spool rack, possibly making it some kind of movable clamp-on design.  The key thing is to make sure that the monitor is mounted securely somewhere so that it can accurately see the travel of filament.  Whether it's secured to the printer or to the filament rack shouldn't matter.

The other issue is that you'll need a longer cable to connect the monitor to your bot...  If you need to, I could rig up an "extension cord" arrangement using two latching connectors back-to-back, plus one more extra cable.

BTW, sorry again for the back-order delay!  We're mostly caught up now!

Joseph

[Dan Newman]

The monitor assumes you use a filament guide tube. If you don't, you can
get false positives such as when the print first starts and the print head
moves to the park and waits for heat up to finish: that can unreel a bunch
of filament through the monitor and then cause no further motion for 2 - 10
minutes while things heat up. That in turn triggers the monitor.

So, to work around that, you need to use a filament guide tube between the
monitor and extruder. That prevents unnecessary amounts of filament from being
fed out of the monitor: filament only gets played out when the extruder stepper
motor runs and pulls it through.

Dan

[Joseph Chiu (Toybuilder)]

The current firmware has a "pre-trigger" dead zone, so the scenario of the initial movement and then heating is unlikely to trigger a pause.  But filament movement from carriage motion may be an issue, depending on the amount of filament tugging...  The current version does not implement any hystersis/sliding window - but that's something I've already thought about adding in the future.

[Bret Wortman]

The delay wasn't a problem at all. And I obviously didn't spend my extra time figuring this issue out!

I'm using this rack: http://www.p3-d.com/overhead-spool-holder.html, but essentially it looks like this (their image):

​

I thought about adding a cross-brace to the rack (between the orange supports in the above image) that would hold the monitor, but then I'm afraid the filament will have to make too tight of a bend to get to the print head, even if I use the tube. I think what I really need is something to sit above the rack so the filament comes up to the monitor, then goes back down into the print head. I think I can throw something together pretty simply in A360 for that.

2020 extrusion is definitely a possibility I hadn't considered, but I'll give that a go too. I think it'd be far more flexible than attaching something to the rack.

And I've got a slew of wire I can use to rig an extension for the cable. No worries there.

Thanks everyone for helping me work this out!

Bret Wortman

[TobyCWood]

Would it work with a config like this?

[Bret Wortman]

Oooh, yes. I like that.

On Nov 23, 2015, at 6:57 PM, TobyCWood <andyc...@gmail.com> wrote:

Would it work with a config like this?

On Sunday, November 22, 2015 at 5:56:50 PM UTC-8, Bret Wortman wrote:

I just purchased a Tunell monitor for my Rep2, and realized as I was preparing to install and mount it that my filament route doesn't come up from behind the replicator, but from an overhead 5-spool rack. I'm trying to figure out the best way to mount the monitor and I'm struggling to come up with ideas, honestly, that will work without interfering with the bot itself. Any thoughts?

<IMG_3484.JPG>

[TobyCWood]

Why Does GGs do that to pics?

[TobyCWood]

So the idea is the same as my thing I did to prevent my spools from unwinding and getting all tangled:

http://www.thingiverse.com/thing:507990

But I went back and made it fit Justin's audible alarm he sells on endlessparts.com for $25.
It is made to fit the prototype supply spool, but you could make it fit any spool pretty easily.

[Bret Wortman]

Thanks!